CN106758813A - For the UHPC wells formula rib floorings and its construction method of steel reinforced concrete composite beam bridge - Google Patents

Abstract

Translated fromChinese

本发明公开了一种用于钢混组合梁桥的UHPC井式肋桥面板及其施工方法，包括预制UHPC井式肋桥面板、矩形柱状槽口、上层钢筋、下层钢筋、簇钉群、高强灌浆料、湿接带钢筋以及湿接带混凝土。其中钢梁翼缘板的上表面沿纵向焊接有簇钉群；工厂化预制UHPC井式肋桥面板；将矩形柱状槽口对准簇钉群安装到钢梁上，在矩形柱状槽口内浇筑高强灌浆料，浇筑湿接带混凝土，使UHPC井式肋桥面板与钢梁连接成整体。本发明的桥面板可发挥UHPC抗压、抗拉强度高的力学特性，利用井式肋和面板组合，有效提高承载力、减小板厚，并取消一般混凝土桥面板中的横向预应力，采用预制安装，现场施工无需底模，高强灌浆料养护时间少，可现场快速化拼装。

The invention discloses a UHPC well rib bridge deck for a steel-concrete composite girder bridge and a construction method thereof. Grouting materials, wet joints with steel bars and wet joints with concrete. Among them, the upper surface of the flange plate of the steel beam is welded with cluster nails along the longitudinal direction; the factory prefabricated UHPC well-rib bridge deck; the rectangular columnar notch is aligned with the cluster nail group and installed on the steel beam, and high-strength grout is poured in the rectangular columnar notch , pouring concrete with wet joints, so that the UHPC well-rib bridge deck and steel beams are connected as a whole. The bridge deck of the present invention can exert the mechanical properties of UHPC with high compressive strength and high tensile strength, utilize the combination of well-shaped ribs and the deck, effectively increase the bearing capacity, reduce the thickness of the deck, and cancel the transverse prestress in the general concrete bridge deck. Prefabricated installation, on-site construction does not require bottom form, high-strength grouting material takes less time to maintain, and can be quickly assembled on site.

Description

Translated fromChinese

用于钢混组合梁桥的UHPC井式肋桥面板及其施工方法UHPC well-rib bridge deck for steel-concrete composite girder bridge and its construction method

技术领域technical field

本发明属于桥梁工程技术领域，具体涉及一种预制UHPC井式肋桥面板的构造及施工，可用作工字形或箱形截面钢混组合梁桥的桥面板。The invention belongs to the technical field of bridge engineering, and in particular relates to the structure and construction of a prefabricated UHPC well-rib bridge deck, which can be used as a bridge deck of an I-shaped or box-shaped steel-concrete composite girder bridge.

背景技术Background technique

钢混组合桥梁是一种有竞争力的桥梁形式，但是，其常用的桥面板构造有钢桥面板和普通混凝土桥面板两种。钢桥面板存在疲劳、开裂和铺装层破损难题，普通混凝土桥面板存在结构厚重、抗拉强度低易于开裂、耐久性差等问题。而超高性能混凝土UHPC(Ultra-High Performance Concrete)，被认为是过去三十年中最具创新性的水泥基工程材料，抗压、抗拉强度高，徐变系数小。与现浇普通混凝土桥面板相比，采用预制的UHPC井式肋桥面板，强度高，收缩徐变量小，耐久性好；同时，可以不设置横向预应力，减轻结构自重，吊装较为容易，可以快速化拼装施工。The steel-concrete composite bridge is a competitive bridge form, but the commonly used bridge deck structures include steel bridge deck and ordinary concrete bridge deck. Steel bridge decks have problems of fatigue, cracking and pavement damage, while ordinary concrete bridge decks have problems such as thick structure, low tensile strength, easy cracking, and poor durability. UHPC (Ultra-High Performance Concrete) is considered to be the most innovative cement-based engineering material in the past three decades, with high compressive and tensile strength and low creep coefficient. Compared with the ordinary cast-in-place concrete bridge deck, the prefabricated UHPC well-rib bridge deck has high strength, small shrinkage and creep variables, and good durability; at the same time, there is no need to set transverse prestress, which reduces the weight of the structure and is easier to hoist. Rapid assembly and construction.

因此，本发明提供了一种创新的桥面板构造及其施工方法，可以克服组合桥梁中传统的钢桥面板和普通混凝土桥面板的一些技术不足。Therefore, the present invention provides an innovative bridge deck structure and its construction method, which can overcome some technical deficiencies of traditional steel bridge decks and ordinary concrete decks in composite bridges.

发明内容Contents of the invention

本发明的目的是提供一种钢混组合梁桥的预制UHPC井式肋桥面板构造，利用UHPC的抗拉、抗压强度高的材料特性，同时构造适当的井式肋，有效地降低了桥面板的厚度。其具有受力性能优异、结构轻巧、不需要配置预应力、可快速拼装施工等优点，还可减轻后期病害，减少后期维护管养工作量。本发明的第二目的在于提供一种钢混组合梁桥UHPC井式肋桥面板的施工方法。The purpose of the present invention is to provide a prefabricated UHPC well-rib bridge deck structure of a steel-concrete composite girder bridge, which utilizes UHPC's high material properties of tensile and compressive strength, and simultaneously constructs appropriate well-ribs, effectively reducing the cost of the bridge. The thickness of the panel. It has the advantages of excellent mechanical performance, light structure, no need for prestressing, fast assembly and construction, etc. It can also reduce later-stage diseases and reduce the workload of later-stage maintenance and management. The second object of the present invention is to provide a construction method for the steel-concrete composite girder bridge UHPC well rib bridge deck.

本发明采用的技术方案为：一种用于钢混组合梁桥的UHPC井式肋桥面板，包括预制UHPC井式肋桥面板、矩形柱状槽口、上层钢筋、下层钢筋、簇钉群、高强灌浆料、湿接带钢筋以及湿接带混凝土；The technical solution adopted in the present invention is: a UHPC well-rib bridge deck for steel-concrete composite girder bridges, including prefabricated UHPC well-rib bridge decks, rectangular columnar notches, upper steel bars, lower steel bars, cluster nail groups, high-strength Grouting materials, wet-joint steel bars and wet-joint concrete;

所述簇钉群焊接在钢梁的翼缘板的上表面，簇钉群沿纵向多排平行设置，多排簇钉群之间相隔相同间距；The cluster nail group is welded on the upper surface of the flange plate of the steel beam, the cluster nail group is arranged in parallel in multiple rows along the longitudinal direction, and the multiple rows of cluster nail groups are separated by the same distance;

所述UHPC井式肋桥面板由井式肋和面板两部分构成，面板中设置上层钢筋和下层钢筋，井式肋内设置肋内钢筋，UHPC井式肋桥面板周边结合面上有预埋的湿接带钢筋露出，UHPC井式肋桥面板上预留有矩形柱状槽口，矩形柱状槽口的位置与所述簇钉群的位置相对应，矩形柱状槽口内穿过的所述上层钢筋保持连续，矩形柱状槽口内浇筑高强灌浆料，使UHPC井式肋桥面板与钢梁连接成整体；相邻UHPC井式肋桥面板之间的湿接带钢筋搭接，并浇筑湿接带混凝土。The UHPC well-rib bridge deck is composed of a well-rib bridge and a face plate. The upper layer of steel bars and the lower layer of steel bars are arranged in the face plate, and the rib inner steel bars are arranged in the well-type ribs. The connecting steel bars are exposed, and a rectangular columnar notch is reserved on the deck of the UHPC well-rib bridge. The position of the rectangular columnar notch corresponds to the position of the cluster nail group. , Pouring high-strength grouting material in the rectangular columnar notch, so that the UHPC well-rib bridge deck and the steel beam are connected as a whole; the wet-joint strip reinforcement between the adjacent UHPC well-rib bridge decks is lapped, and the wet-joint concrete is poured.

作为优选，所述井式肋高度H1＝22～30cm，面板厚度为H2＝12～20cm；横桥向：井式肋宽度B1＝10～15cm；纵桥向：井式肋底口宽度B2＝40～60cm，倒角坡度i＝1:1.5～1:2。Preferably, the well rib height H1=22-30cm, the panel thickness H2=12-20cm; horizontal bridge direction: well rib width B1=10-15cm; longitudinal bridge direction: well rib bottom opening width B2= 40~60cm, chamfering slope i=1:1.5~1:2.

上述用于钢混组合梁桥的UHPC井式肋桥面板的施工方法，包括如下步骤：The above-mentioned construction method for the UHPC well-rib bridge deck for steel-concrete composite girder bridges comprises the following steps:

1)工厂化制作UHPC井式肋桥面板，面板中设置上层钢筋和下层钢筋，井式肋内设置肋内钢筋，使用UHPC混凝土预制而成，其周边结合面上有预埋的湿接带钢筋露出，在对应簇钉群位置的UHPC井式肋桥面板上，预留有矩形柱状槽口，在矩形柱状槽口内预制UHPC井式肋桥面板的上层钢筋保持连续；1) The UHPC well-rib bridge deck is manufactured in a factory. The upper and lower steel bars are set in the panel, and the inner ribs are set in the well rib. It is prefabricated with UHPC concrete, and there are pre-buried wet-bonded steel bars on the peripheral joint surface. For exposure, a rectangular columnar notch is reserved on the UHPC well-rib bridge deck corresponding to the position of the cluster nail group, and the upper steel bars of the prefabricated UHPC well-rib bridge deck are kept continuous in the rectangular columnar notch;

2)安装钢梁，钢梁翼缘板上表面以相同间距焊接有簇钉群，将预制UHPC井式肋桥面板的矩形柱状槽口对准簇钉群安装到钢梁上，并使相邻UHPC井式肋桥面板之间的湿接带钢筋搭接；2) Install the steel girder, the upper surface of the flange plate of the steel girder is welded with cluster nail groups at the same interval, align the rectangular columnar notch of the prefabricated UHPC well rib bridge deck with the cluster nail group and install it on the steel beam, and make the adjacent UHPC well Wet joints with reinforcement laps between the decks of double-rib bridges;

3)在矩形柱状槽口内浇筑高强灌浆料，使UHPC井式肋桥面板与钢梁连接成整体，保温保湿养护5～7天。3) Pour high-strength grouting material in the rectangular columnar notches, so that the UHPC well-ribbed bridge deck and steel beams are connected as a whole, and the heat preservation and moisturizing maintenance is carried out for 5 to 7 days.

4)安装所述UHPC井式肋桥面板之间的湿接带钢筋，吊装湿接带部分的底模板，浇筑湿接带混凝土，保温保湿养护7～14天，即可投入使用。4) Install the wet-joint reinforcing bars between the decks of the UHPC well-rib bridge, hoist the bottom formwork of the wet-joint part, pour the wet-joint concrete, keep it warm and moist for 7 to 14 days, and then it can be put into use.

与现有技术相比，本发明具有如下有益效果：Compared with the prior art, the present invention has the following beneficial effects:

1、本发明采用UHPC井式肋桥面板构造，充分利用UHPC的抗拉、抗压强度高的材料特性，取消了桥面板的横向预应力。1. The present invention adopts UHPC well-rib bridge deck structure, fully utilizes the material properties of UHPC with high tensile and compressive strength, and cancels the transverse prestress of the bridge deck.

2、设计适当的井式肋构造，有效地降低了桥面板的厚度，减少了结构自重使结构变得轻巧。2. The well-shaped rib structure is designed properly, which effectively reduces the thickness of the bridge deck, reduces the self-weight of the structure and makes the structure light.

3、预制安装UHPC井式肋桥面板，实现了钢-混组合梁现浇桥面板的无支架施工，使现场拼装施工快速方便。3. Prefabrication and installation of UHPC well-rib bridge deck realizes the construction of steel-concrete composite girder cast-in-place bridge deck without support, making the on-site assembly construction fast and convenient.

4、通过簇钉群和高强灌浆料把钢梁和UHPC井式肋桥面板紧密连接起来，形成了整体受力结构，充分发挥钢-混结构的材料性能。4. The steel girder and the UHPC well-rib bridge deck are tightly connected by cluster nails and high-strength grouting materials, forming an overall force-bearing structure and giving full play to the material properties of the steel-concrete structure.

附图说明Description of drawings

图1是本发明的UHPC井式肋桥面板构造横断面图。Fig. 1 is a cross-sectional view of the UHPC well rib bridge deck structure of the present invention.

图2是本发明的预制UHPC井式肋桥面板横断面图。Fig. 2 is a cross-sectional view of the prefabricated UHPC well rib bridge deck of the present invention.

图3是图2中A-A断面图。Fig. 3 is a sectional view of A-A in Fig. 2 .

图4是本发明的UHPC井式肋桥面板安装示意图。Fig. 4 is a schematic diagram of installation of the UHPC well rib bridge deck of the present invention.

图5是本发明的UHPC井式肋桥面板间安装前示意图。Fig. 5 is a schematic view before installation between the UHPC well rib bridge decks of the present invention.

图6是本发明的UHPC井式肋桥面板间安装后示意图。Fig. 6 is a schematic diagram after installation between the UHPC well rib bridge decks of the present invention.

图7是本发明的UHPC井式肋桥面板间湿接带示和灌浆意图。Fig. 7 is the diagram of the wet joint between the decks of the UHPC well-rib bridge of the present invention and the grouting diagram.

具体实施方式detailed description

下面结合附图和具体实施方式对本发明作更进一步的说明。The present invention will be further described below in conjunction with the accompanying drawings and specific embodiments.

如图1-7所示，一种用于钢混组合梁桥的UHPC井式肋桥面板，包括预制UHPC井式肋桥面板4、矩形柱状槽口5、上层钢筋8、下层钢筋9、簇钉群3、高强灌浆料10、湿接带钢筋11以及湿接带混凝土12；As shown in Figure 1-7, a UHPC well-rib bridge deck for steel-concrete composite girder bridges includes prefabricated UHPC well-rib bridge deck 4, rectangular columnar notch 5, upper reinforcement 8, lower reinforcement 9, clusters Nail group 3, high-strength grouting material 10, wet-joint steel bar 11 and wet-joint concrete 12;

所述簇钉群3焊接在钢梁1的翼缘板2的上表面，簇钉群3沿纵向多排平行设置，多排簇钉群3之间相隔相同间距；The cluster nail group 3 is welded on the upper surface of the flange plate 2 of the steel beam 1, the cluster nail group 3 is arranged in parallel in multiple rows along the longitudinal direction, and the multiple rows of cluster nail groups 3 are separated by the same distance;

所述UHPC井式肋桥面板4由井式肋6和面板两部分构成，面板中设置上层钢筋8和下层钢筋9，井式肋6内设置肋内钢筋7，UHPC井式肋桥面板4周边结合面上有预埋的湿接带钢筋11露出，UHPC井式肋桥面板4上预留有矩形柱状槽口5，矩形柱状槽口5的位置与所述簇钉群3的位置相对应，矩形柱状槽口5内穿过的所述上层钢筋8保持连续，矩形柱状槽口5内浇筑高强灌浆料10，使UHPC井式肋桥面板4与钢梁1连接成整体；相邻UHPC井式肋桥面板4之间的湿接带钢筋11搭接，并浇筑湿接带混凝土12。The UHPC well-rib bridge deck 4 is composed of two parts: the well-rib bridge 6 and the face plate. The upper layer steel bar 8 and the lower layer steel bar 9 are arranged in the face plate. There are pre-buried wet-joint steel bars 11 exposed on the surface, and a rectangular columnar notch 5 is reserved on the UHPC well rib bridge deck 4. The position of the rectangular columnar notch 5 corresponds to the position of the cluster nail group 3. The upper steel bar 8 passing through the columnar notch 5 remains continuous, and the high-strength grouting material 10 is poured in the rectangular columnar notch 5, so that the UHPC well-rib bridge deck 4 and the steel beam 1 are connected as a whole; the adjacent UHPC well-rib The wet-joint steel bars 11 between the bridge decks 4 are overlapped, and the wet-joint concrete 12 is poured.

所述井式肋6高度H1＝22～30cm，面板厚度为H2＝12～20cm；横桥向：井式肋6宽度B1＝10～15cm；纵桥向：井式肋6底口宽度B2＝40～60cm，倒角坡度i＝1:1.5～1:2。The height of the well rib 6 is H1=22～30cm, and the thickness of the panel is H2=12～20cm; the horizontal bridge direction: the well rib 6 width B1=10～15cm; the longitudinal bridge direction: the well rib 6 bottom opening width B2= 40~60cm, chamfering slope i=1:1.5~1:2.

上述用于钢混组合梁桥的UHPC井式肋桥面板的施工方法，包括如下步骤：The above-mentioned construction method for the UHPC well-rib bridge deck for steel-concrete composite girder bridges comprises the following steps:

1)工厂化制作UHPC井式肋桥面板4，面板中设置上层钢筋8和下层钢筋9，井式肋6内设置肋内钢筋7，使用UHPC混凝土预制而成，其周边结合面上有预埋的湿接带钢筋11露出，在对应簇钉群3位置的UHPC井式肋桥面板4上，预留有矩形柱状槽口5，在矩形柱状槽口5内预制UHPC井式肋桥面板4的上层钢筋8保持连续；1) The UHPC well-rib bridge deck 4 is manufactured in a factory. The upper steel bar 8 and the lower steel bar 9 are set in the panel. The wet-jointed steel bars 11 are exposed, and a rectangular columnar notch 5 is reserved on the UHPC well-rib bridge deck 4 corresponding to the position of the cluster nail group 3, and the UHPC well-rib bridge deck 4 is prefabricated in the rectangular columnar notch 5 The upper layer of reinforcement 8 remains continuous;

2)安装钢梁1，钢梁1翼缘板2上表面以一定间距焊接有簇钉群3，将预制UHPC井式肋桥面板4的矩形柱状槽口5对准簇钉群3安装到钢梁1上，并使相邻UHPC井式肋桥面板4之间的湿接带钢筋11搭接；2) Install the steel girder 1, the upper surface of the flange plate 2 of the steel girder 1 is welded with cluster nail groups 3 at a certain interval, and align the rectangular columnar notch 5 of the prefabricated UHPC well rib bridge deck 4 with the cluster nail group 3 and install it on the steel beam 1. Beam 1, and make the wet joint belt reinforcement 11 between the adjacent UHPC well rib bridge decks 4 overlap;

3)在矩形柱状槽口5内浇筑高强灌浆料10，使UHPC井式肋桥面板4与钢梁1连接成整体，保温保湿养护5～7天。3) Pour high-strength grouting material 10 in the rectangular columnar notch 5, so that the UHPC well-rib bridge deck 4 and the steel beam 1 are connected as a whole, and the heat preservation and moisturizing maintenance are carried out for 5 to 7 days.

4)安装所述UHPC井式肋桥面板4之间的湿接带钢筋11，吊装湿接带部分的底模板，浇筑湿接带混凝土12，保温保湿养护7～14天，即可投入使用。4) Install the wet-joint steel bars 11 between the UHPC well-rib bridge decks 4, hoist the bottom formwork of the wet-joint part, pour the wet-joint concrete 12, keep it warm and moist for 7 to 14 days, and then it can be put into use.

应当指出，对于本技术领域的普通技术人员来说，在不脱离本发明原理的前提下，还可以做出若干改进和润饰，这些改进和润饰也应视为本发明的保护范围。本实施例中未明确的各组成部分均可用现有技术加以实现。It should be pointed out that those skilled in the art can make some improvements and modifications without departing from the principle of the present invention, and these improvements and modifications should also be regarded as the protection scope of the present invention. All components that are not specified in this embodiment can be realized by existing technologies.

Claims (3)

Translated fromChinese

1.一种用于钢混组合梁桥的UHPC井式肋桥面板，其特征在于：包括预制UHPC井式肋桥面板、矩形柱状槽口、上层钢筋、下层钢筋、簇钉群、高强灌浆料、湿接带钢筋以及湿接带混凝土；1. A UHPC well-rib bridge deck for steel-concrete composite girder bridge, characterized in that: comprise prefabricated UHPC well-rib bridge deck, rectangular column notch, upper reinforcement, lower reinforcement, cluster nail group, high-strength grouting material , Wet joint with steel bars and wet joint with concrete;所述簇钉群焊接在钢梁的翼缘板的上表面，簇钉群沿纵向多排平行设置，多排簇钉群之间相隔相同间距；The cluster nail group is welded on the upper surface of the flange plate of the steel beam, the cluster nail group is arranged in parallel in multiple rows along the longitudinal direction, and the multiple rows of cluster nail groups are separated by the same distance;所述UHPC井式肋桥面板由井式肋和面板两部分构成，面板中设置上层钢筋和下层钢筋，井式肋内设置肋内钢筋，UHPC井式肋桥面板周边结合面上有预埋的湿接带钢筋露出，UHPC井式肋桥面板上预留有矩形柱状槽口，矩形柱状槽口的位置与所述簇钉群的位置相对应，矩形柱状槽口内穿过的所述上层钢筋保持连续，矩形柱状槽口内浇筑高强灌浆料，使UHPC井式肋桥面板与钢梁连接成整体；相邻UHPC井式肋桥面板之间的湿接带钢筋搭接，并浇筑湿接带混凝土。The UHPC well-rib bridge deck is composed of a well-rib bridge and a face plate. The upper layer of steel bars and the lower layer of steel bars are arranged in the face plate, and the rib inner steel bars are arranged in the well-type ribs. The connecting steel bars are exposed, and a rectangular columnar notch is reserved on the deck of the UHPC well-rib bridge. The position of the rectangular columnar notch corresponds to the position of the cluster nail group. , Pouring high-strength grouting material in the rectangular columnar notch, so that the UHPC well-rib bridge deck and the steel beam are connected as a whole; the wet-joint strip reinforcement between the adjacent UHPC well-rib bridge decks is lapped, and the wet-joint concrete is poured.2.根据权利要求1所述的用于钢混组合梁桥的UHPC井式肋桥面板，其特征在于：所述井式肋高度H1＝22～30cm，面板厚度为H2＝12～20cm；横桥向：井式肋宽度B1＝10～15cm；纵桥向：井式肋底口宽度B2＝40～60cm，倒角坡度i＝1:1.5～1:2。2. The UHPC well rib bridge deck for steel-concrete composite girder bridge according to claim 1, characterized in that: the well rib height H1=22～30cm, the panel thickness H2=12～20cm; Bridge direction: well rib width B1=10~15cm; longitudinal bridge direction: well rib bottom opening width B2=40~60cm, chamfer slope i=1:1.5~1:2.3.根据权利要求1所述的用于钢混组合梁桥的UHPC井式肋桥面板的施工方法，其特征在于：包括如下步骤：3. the construction method of the UHPC well rib bridge deck for steel-concrete composite girder bridge according to claim 1, is characterized in that: comprise the steps:1)工厂化制作UHPC井式肋桥面板，面板中设置上层钢筋和下层钢筋，井式肋内设置肋内钢筋，使用UHPC混凝土预制而成，其周边结合面上有预埋的湿接带钢筋露出，在对应簇钉群位置的UHPC井式肋桥面板上，预留有矩形柱状槽口，在矩形柱状槽口内预制UHPC井式肋桥面板的上层钢筋保持连续；1) The UHPC well-rib bridge deck is manufactured in a factory. The upper and lower steel bars are set in the panel, and the inner ribs are set in the well rib. It is prefabricated with UHPC concrete, and there are pre-buried wet-bonded steel bars on the peripheral joint surface. For exposure, a rectangular columnar notch is reserved on the UHPC well-rib bridge deck corresponding to the position of the cluster nail group, and the upper steel bars of the prefabricated UHPC well-rib bridge deck are kept continuous in the rectangular columnar notch;2)安装钢梁，钢梁翼缘板上表面以相同间距焊接有簇钉群，将预制UHPC井式肋桥面板的矩形柱状槽口对准簇钉群安装到钢梁上，并使相邻UHPC井式肋桥面板之间的湿接带钢筋搭接；2) Install the steel girder, the upper surface of the flange plate of the steel girder is welded with cluster nail groups at the same interval, align the rectangular columnar notch of the prefabricated UHPC well rib bridge deck with the cluster nail group and install it on the steel beam, and make the adjacent UHPC well Wet joints with reinforcement laps between the decks of double-rib bridges;3)在矩形柱状槽口内浇筑高强灌浆料，使UHPC井式肋桥面板与钢梁连接成整体，保温保湿养护5～7天；3) Pour high-strength grouting material in the rectangular columnar notch, so that the UHPC well-rib bridge deck and the steel beam are connected as a whole, and the heat preservation and moisturizing maintenance is carried out for 5 to 7 days;4)安装所述UHPC井式肋桥面板之间的湿接带钢筋，吊装湿接带部分的底模板，浇筑湿接带混凝土，保温保湿养护7～14天，即可投入使用。4) Install the wet-joint reinforcing bars between the decks of the UHPC well-rib bridge, hoist the bottom formwork of the wet-joint part, pour the wet-joint concrete, keep it warm and moist for 7 to 14 days, and then it can be put into use.